The disclosures herein relate generally to the field of control systems for work vehicles. More particularly, the disclosures herein relate to a system and method for quickly determining the threshold control current necessary to actuate a proportional control system such as a hydro-mechanical system on a work vehicle.
To operate a modern hydraulic control system it is important to determine the startup threshold current of devices such as pumps, clutches, valves and other mechanisms which are controlled via control signals. These devices have a common operating requirement, namely that they all require some minimum amount of current, i.e. the startup threshold current, to start operating. The conventional approach to determining such startup threshold currents is to employ an automatic calibration process to measure the startup threshold current for a hydraulic system by ramping up the control signal slowly until the controlled device starts to move. This ramping step is repeated several times and the results are averaged to yield an average startup threshold current. Unfortunately, this calibration process takes a relatively large amount of time to obtain accurate results. Since hydraulic systems exhibit system dynamics and nonlinear characteristics, the ramp up speed is essential to the accuracy of threshold current calibration.
What is needed is a methodology for more quickly automatically determining the startup threshold currents for controlled devices without sacrificing calibration accuracy. Such a methodology would be especially useful in work vehicles such as combines and other agricultural implements requiring calibration of their hydraulic, pneumatic and other proportional control systems.